Mitsubishi Electric Q12DCCPU-V User Manual page 168

5
ACCESS VIA NETWORK MODULES
5
- 14 5.3 MELSECNET/H Module Access Function
5.3.1 Message communication
POINT
Pay attention to the following when sending a message to a MELSECNET/H
module controlled by a programmable controller CPU.
When sending data twice to the same channel of the receiving station with ACK
set, execute the second transmission after the receiving station has read out the
first data by the RECV instruction.
Failure to do so will cause an error. If an error is detected, retry the transmission
after a little while.
C Controller module
(Sending station)
User program
ret = QBF_SEND();
ret = QBF_SEND();
MELSECNET/H module
Channel 3
Error
CPU (Receiving
Network module
station)
Logical channel
(Channel 5)
RECV